TY - JOUR
T1 - Geography is more important than life history in the recent diversification of the tiger salamander complex
AU - Everson, Kathryn M.
AU - Gray, Levi N.
AU - Jones, Angela G.
AU - Lawrence, Nicolette M.
AU - Foley, Mary E.
AU - Sovacool, Kelly L.
AU - Kratovil, Justin D.
AU - Hotaling, Scott
AU - Hime, Paul M.
AU - Storfer, Andrew
AU - Parra-Olea, Gabriela
AU - Percino-Daniel, Ruth
AU - Aguilar-Miguel, X.
AU - O’Neill, Eric M.
AU - Zambrano, Luis
AU - Bradley Shaffer, H.
AU - Weisrock, David W.
N1 - Funding Information:
This project was supported by grants from the NSF (DEB-0949532, DEB-1355000, and DEB-1406876 [DDIG awarded to J.D.K.]) and by a University Research Fellowship awarded to K.M.E. from the University of Kentucky. We thank Chris Beachy, Jim Bogart, Ken Carbale, Sheri Church, Jeff LeClere, Carol Hall, Paul Moler, Nancy Staub, and Ken Wray for genetic samples and Jose Bocanegra, Ben Browning, Mackenzie Humphrey, Mary Virginia Gibbs, Ricky Grewelle, Alan Lemmon, Emily Moriarty Lemmon, Deborah Lu, Stephanie Mitchell, Alex Noble, Tolu Odukoya, Ben Tuttle, and Josh Williams for assistance with data collection and analyses.
Funding Information:
ACKNOWLEDGMENTS. This project was supported by grants from the NSF (DEB-0949532, DEB-1355000, and DEB-1406876 [DDIG awarded to J.D.K.]) and by a University Research Fellowship awarded to K.M.E. from the University of Kentucky. We thank Chris Beachy, Jim Bogart, Ken Carbale, Sheri Church, Jeff LeClere, Carol Hall, Paul Moler, Nancy Staub, and Ken Wray for genetic samples and Jose Bocanegra, Ben Browning, Mackenzie Humphrey, Mary Virginia Gibbs, Ricky Grewelle, Alan Lemmon, Emily Moriarty Lemmon, Deborah Lu, Stephanie Mitchell, Alex Noble, Tolu Odukoya, Ben Tuttle, and Josh Williams for assistance with data collection and analyses.
Publisher Copyright:
© 2021 National Academy of Sciences. All rights reserved.
PY - 2021/4/27
Y1 - 2021/4/27
N2 - The North American tiger salamander species complex, including its best-known species, the Mexican axolotl, has long been a source of biological fascination. The complex exhibits a wide range of variation in developmental life history strategies, including populations and individuals that undergo metamorphosis; those able to forego metamorphosis and retain a larval, aquatic lifestyle (i.e., paedomorphosis); and those that do both. The evolution of a paedomorphic life history state is thought to lead to increased population genetic differentiation and ultimately reproductive isolation and speciation, but the degree to which it has shaped population- and species-level divergence is poorly understood. Using a large multilocus dataset from hundreds of samples across North America, we identified genetic clusters across the geographic range of the tiger salamander complex. These clusters often contain a mixture of paedomorphic and metamorphic taxa, indicating that geographic isolation has played a larger role in lineage divergence than paedomorphosis in this system. This conclusion is bolstered by geography-informed analyses indicating no effect of life history strategy on population genetic differentiation and by model-based population genetic analyses demonstrating gene flow between adjacent metamorphic and paedomorphic populations. This fine-scale genetic perspective on life history variation establishes a framework for understanding how plasticity, local adaptation, and gene flow contribute to lineage divergence. Many members of the tiger salamander complex are endangered, and the Mexican axolotl is an important model system in regenerative and biomedical research. Our results chart a course for more informed use of these taxa in experimental, ecological, and conservation research.
AB - The North American tiger salamander species complex, including its best-known species, the Mexican axolotl, has long been a source of biological fascination. The complex exhibits a wide range of variation in developmental life history strategies, including populations and individuals that undergo metamorphosis; those able to forego metamorphosis and retain a larval, aquatic lifestyle (i.e., paedomorphosis); and those that do both. The evolution of a paedomorphic life history state is thought to lead to increased population genetic differentiation and ultimately reproductive isolation and speciation, but the degree to which it has shaped population- and species-level divergence is poorly understood. Using a large multilocus dataset from hundreds of samples across North America, we identified genetic clusters across the geographic range of the tiger salamander complex. These clusters often contain a mixture of paedomorphic and metamorphic taxa, indicating that geographic isolation has played a larger role in lineage divergence than paedomorphosis in this system. This conclusion is bolstered by geography-informed analyses indicating no effect of life history strategy on population genetic differentiation and by model-based population genetic analyses demonstrating gene flow between adjacent metamorphic and paedomorphic populations. This fine-scale genetic perspective on life history variation establishes a framework for understanding how plasticity, local adaptation, and gene flow contribute to lineage divergence. Many members of the tiger salamander complex are endangered, and the Mexican axolotl is an important model system in regenerative and biomedical research. Our results chart a course for more informed use of these taxa in experimental, ecological, and conservation research.
KW - Ambystoma
KW - Life history
KW - Phylogenetics
KW - Population genomics
KW - Salamanders
UR - http://www.scopus.com/inward/record.url?scp=85105359819&partnerID=8YFLogxK
U2 - 10.1073/pnas.2014719118
DO - 10.1073/pnas.2014719118
M3 - Article
C2 - 33888580
AN - SCOPUS:85105359819
SN - 0027-8424
VL - 118
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 17
M1 - e2014719118
ER -